A puncture can sit perfectly inside the T-zone and the tyre can still belong in the bin. The repairable zone tells you whether the hole can be fixed. The casing tells you whether the tyre is worth fixing. This is the list of what sends the whole tyre to scrap, regardless of where the puncture is.
- Sidewall or shoulder damage. Any puncture, cut or bulge outside the T-zone. These areas flex and a repair there won't hold.
- Bead damage. A torn or distorted bead won't seat and seal on the rim safely. If the bead is chewed up from a botched dismount, the tyre is done.
- Run-flat casing damage. A tyre driven under-inflated or flat has overheated and delaminated internally, even if it looks fine from the outside. The damage is inside the casing where you can't see it until the tyre comes off the rim.
- Exposed or bulged casing plies. The structural cord is visible, or the casing has a lump that means the belt has shifted. The structure has already failed.
- Tread depth below the wear limit. Repairing a tyre that's nearly illegal is false economy. The customer is paying for a repair on a tyre they'll replace in weeks.
- A previous repair outside the limits. A tyre already repaired in the shoulder, or patched twice in the same spot, has used up its repair allowance.
